1. Field of the Invention
The present invention is directed to a method for confirming patient's complaints as manifestations of a physiological condition. More particularly, the present invention is directed to a urodynamic technique for confirming a patient's complaint with respect to the bladder (e.g., urge or cramp) as a manifestation of a physiological condition; and apparatus for effecting such methodology.
2. Description of the Prior Art
In clinical cystometry, intraluminal pressure is recorded in relation to bladder volume (Griffiths, D. J., et al., "Detrusor Instability In Children", Neurourol. Urodyn. 1, 187-192 (1982); Abrams, P., "Detrusor Instability And Bladder Outlet Obstruction", Neurourol. Urodyn., 4, 317-328 (1985); Coolsaet, B. L. R. A., "Bladder Compliance And Detrusor Activity During The Collection Phase", Neurourol. Urodyn., 4, 263-273 (1985)). Often, spontaneous phasic and tonic variations in intraluminal pressure are observed (International Continence Society: Fourth Report On The Standardization Of Terminology Of Lower Urinary Tract Function, J. Urol., 53, 333 (1980)). It was noticed that the spontaneous variation in detrusor pressure in the normal human bladder did not occur until a relatively high volume was obtained (Plum, F., "Autonomous Urinary Bladder Activity In Normal Man", Neurol. 2, 497-503 (1960)); and it was hypothesized that the onset of the micturition reflex was triggered by these spontaneous contractions via afferent stimuli (Plum, F., et al., "The Genesis Of Vesical Rhythmicity", A.M.A. Archives of Neurology, Vol. 2, 487-496 (1960)). A certain amount of spontaneous variation in pressure, sometimes expressed as an "instability index": is assumed to be related to symptoms of urge (Murray, K., et al., "The Effect Of Opioid Blockade On Idiopathic Detrusor Instability", Proc. 12th Ann. Meeting, Leiden, 85-87 (1982)). In particular, when large spontaneous phasic pressure waves are seen during cystometry (e.g., larger than 15 cm H.sub.2 O), urge is labelled as motor urge. The spontaneous activity observed in situ is supposed to be neurogenic (Griffiths, D. J., et al., "Urinary Bladder Function And Its Control In Healthy Females" Am. J. Physiol., 251, R225-230 (1986)). Hence, the spontaneous activity observed in vivo (bladder instability) is supposed to have an origin other than that of the spontaneous activity observed in vitro.
A recent model, based on observations on total pig bladders in vitro and on observations in patients, suggests the spontaneous activity seen in vitro is normally neurally inhibited in vivo and may become manifest in cases of disturbed neural control (Coolsaet, B. L. R. A., et al., "New Concepts In Relation To Urge And Detrusor Activity" Neurourol Urodyn., 12, 463-471 (1993); Van Duyl, W. A., et al., "Evocation Of Unstable Detrusor Contractions By Stretch", Submitted to Eur. J. Urology (1994); Van OsBossagh, P., et al., "Filling State Of Bladder And Bladder Wall Activity: A Functional Model", Submitted To Neurourol. Urodyn. (1994)).
Conventionally, the main interest of urodynamic research has been to find techniques to confirm the patient's complaint of urge in terms of pressure. The causal relation between urge symptoms and detrusor over-activity has been clinically evaluated in several studies. To increase the chance of verification of the patient's complaint in terms of bladder pressure, ambulatory urodynamics (Waalwijk van Doorn, E. S. C., et al., "A Retrospective Study Of The Clinical Value Of Telemetric Urodynamics Compared With Standard Urodynamics In Patients With Urinary Incontinence", Biotelemetry IX, 159-160, H. P. Kimmich and M. R. Newman, Eds. (1987)) and provocative tests (Coolsaet, B. L. R. A., et al., "Detrusor Overactivity", Neurourol. Urodyn., 5, 435-447 (1988)) are performed. Despite these improved techniques, there is a poor correlation between detrusor pressure and clinical symptoms (Jorgensen, L., et al., "Vaginal Repair In Female Motor Urge Incontinence", Eur. Urol, 13, 2, 382 (1978)). The poor correlation between detrusor pressure and urge might be explained by the fact that detrusor pressure is an incomplete reflection of relevant phenomena in the bladder wall.
The concept of micromotion refers to the phenomenon of distributed spontaneous contraction activity in smooth muscle, particularly, of the urinary bladder (Van Duyl W. A., "Spontaneous Contractions In Urinary Bladder Smooth Muscle: Preliminary Results", Neurourol. Urodyn., 4, 301-308 (1985)). Several techniques have been published to measure minute displacements in tissue (Paolini, P. J., et al., "Dual diffractometer utilizing linear image sensor charge-coupled devices", Rev. Sci. Instr., 47, 698-702 (1976); and Roos, K. P., et al., "Individual Sarcomere Length Determinations From Isolated Cardiac Cells Using High Resolution Optical Microscopy And Digital Image Processing", Biophys. J., 40, 233-244 (1982)). To study (micro-) displacements in striated muscle, use can be made of the structure (sarcomeres) as landmarks for reference (Drake, A. D., et al., "A Fiber Fizeau Interferometer For Measuring Minute Biological Displacements", I.E.E.E. Trans. Biomed. Eng., BME-31, No 7, 507-511(1984)). Because smooth muscle lacks such a structure for reference, it is necessary to use markers to measure the (distribution of) micromotion in a strip. The displacement of such markers can be measured by means of a videotechnique (Hoffman, A., et al., "A Method For Measuring Strains In Soft Tissue", J. Biomech., Vol. 12, No. 10, 795-800 (1984)).
Micromotion patterns were observed in studies, in vitro, on strips of pig bladder tissue. As markers, light spots realized by thin optical fibers stuck through the tissue, were utilized; the local excursions being observed by means of the displacement of the fibertips. The fibertips could be followed by a video system, however, to analyze the motions, it was preferred to use a position-sensitive planar semi-conductor. By means of this technique, micromotions were observed with a resolution of approximately 50 .mu.m (Van Duyl, W. A., "Spontaneous Contractions In Urinary Bladder Smooth Muscle: Preliminary Results", Neurourol. Urodyn., 4, 301-308 (1985); and Van Duyl, W. A., et al., "A Fiber Technique To Measure Patterns Of Micromotion In Strips Of Tissue" (In Preparation (1994)).
In the literature, many authors have reported spontaneous contractions observed, in vitro, as variations of force across a strip of smooth muscle (e.g., Levin, R. B., et al., "Relevance Of Spontaneous Activity To Urinary Bladder Function: An In Vitro And An In Vivo Study", J. Urol., 136, 514-521 (1986)) It has been shown that these spontaneous contractions of strips of the bladder (rabbit bladder) are different for longitudinal and transverse strips taken from the lower-, mid- and upper-part of the bladder (Potjer, R. M., et al., "Frequency Of Spontaneous Contractions In Longitudinal And Transverse Bladder Strips", Am. J. Physiol., 257, R781-R787 (1989)).
However, most authors take the spontaneous activity as an artifact and, hence, do not consider it to be physiologically relevant for in situ situations. Some authors mention the possibility of using the observation of spontaneous activity for pharmacological studies, in vitro. Nonetheless, spontaneous activity, in vitro, is considered to be a myogenic artifact.